#include<bits/stdc++.h>
using namespace std;
int main(){
	freopen("cipher.in" , "r" , stdin);
	freopen("cipher.out" , "w" , stdout);
	int n;
	cin >> n;
	string s;
	cin >> s;
	for(int i = 0 ; i < s.length() ; i++){
		cout << char((s[i] - 'a' + n) % 26 + 'a');
	}
	return 0;
}